Two generally recognized classes of yarn are spun yarns and filament yarns. Spun yarns are typically formed by techniques such as open end spinning, ring spinning and air-jet spinning in which relatively short staple fibers having lengths in the range of about several inches are bound together in a generally stable yarn structure by twist between the discrete staple fibers. Due to the relatively short length of the staple fibers, a portion of the staple fibers tend to project away from the main body of the yarn thereby imparting a textured or hairy surface. Such a textured surface may be desirable to impart a generally soft feel to the yarn and the fabrics formed therefrom.
Filament yams are generally composed from an assemblage of so-called continuous or endless filaments of substantial length which are assembled together by practices such as air-jet entanglement or the like. Such filament yams have the advantage of being produceable from substantially continuous lengths of polymer filaments without requiring such filaments to be cut into discrete staple lengths and undergoing a spinning operation. However, due to the continuous nature of the filaments used in a filament yam, such a yarn is typically substantially free of upstanding fibers defining hair along its length. Thus, the texture of a traditional filament yarn is substantially different from that of a spun yam. Fabrics formed from traditional filament yams may thus have a smooth untextured appearance and may lack the soft hand characteristics which may be desirable in applications where physical contact is contemplated.
In the past, attention has been given to finding appropriate methods by which the desirable characteristics of conventional spun yam, (e.g. appearance, bulk and hand) may be imparted to synthetic continuous filament yam. In particular, known processes exist for sanding fabrics formed from filament yams so as to raise fibrils along the filaments forming the yams. It is also known to subject filament yams to so-called “false twist texturing” or “air-jet texturing” in which the yarn is treated to impart bulk and texture as will be well known to those of skill in the art. It is also known to impart high bulk characteristics to yams to produce a so called “core and effect yam” to yield an arrangement of loops and the like on the periphery of the yam core. While these various processes are both useful and advantageous to increase the apparent volume of a filament yam, such techniques typically do not yield substantial numbers of outwardly projecting hair-like elements around the yarn surface and thus do not substantially simulate the characteristics of a traditional spun yarn. That is, while the bulked filaments at the surface of such treated yarns provide the benefit of enhancing bulk in the yarn while also improving the perceived tactile character, the hand of fabrics formed from such false twist yarn may still be inferior to that of spun yarns due to the generally smooth profile of the loops and the lack of hairiness from discrete fiber segments projecting outwardly away from the yarn.
Aside from the known bulking operations, it has also been proposed to utilize various treatments to break surface filaments by frictional forces to impart a degree of hairiness along the yarn length. However, such practices have typically required relatively complex arrangements of equipment which do not treat the entire surface of the yarn and which are susceptible to the risk of damaging the yarn unless the processes are operated with substantial control. Exemplary processes which utilize a series of rolls for carrying a bulked yarn and pulling a portion of the surface fibers away from the bulked yarn to enlarge and/or break those surface fibers are illustrated and described in U.S. Pat. Nos. 4,501,046 and 6,012,206 the contents of which are incorporated by reference as if fully set forth herein. In such processes, the surface filaments are primarily pulled away from the periphery of the yarn with breakage being only incidental to the pulling action as filaments are stretched beyond their breaking point. Accordingly, such processes yield a relatively small number of broken filaments of substantial length. Moreover, since the pulling action is highly dependent upon the yarn itself as the friction inducing component, changes in the yarn such as changes in denier, tension, etc. require relatively complex adjustment. A further drawback is that operation of such a device requires a highly skilled operator.